Wells Peter P, Qian Yangdong, King Colin R, Wiltshire Richard J K, Crabb Eleanor M, Smart Lesley E, Thompsett David, Russell Andrea E
School of Chemistry, University of Southampton, Highfield, Southampton, UK SO17 1BJ.
Faraday Discuss. 2008;138:273-85; discussion 317-35, 433-4. doi: 10.1039/b707353b.
The cathode electrocatalysts for proton exchange membrane (PEM) fuel cells are commonly platinum and platinum based alloy nanoparticles dispersed on a carbon support. Control over the particle size and composition has, historically, been attained empirically, making systematic studies of the effects of various structural parameters difficult. The controlled surface modification methodology used in this work has enabled the controlled modification of carbon supported Pt nanoparticles by Cr so as to yield nanoalloy particles with defined compositions. Subsequent heat treatment in 5% H2 in N2 resulted in the formation of a distinct Pt3Cr alloy phase which was either restricted to the surface of the particles or present throughout the bulk of the particle structure. Measurement of the oxygen reduction activity of the catalysts was accomplished using the rotating thin film electrode method and the activities obtained were related to the structure of the nanoalloy catalyst particles, largely determined using Cr K edge and Pt L3 edge XAS.
用于质子交换膜（PEM）燃料电池的阴极电催化剂通常是分散在碳载体上的铂及铂基合金纳米颗粒。从历史上看，对颗粒尺寸和组成的控制是通过经验实现的，这使得对各种结构参数的影响进行系统研究变得困难。本工作中使用的可控表面改性方法能够通过Cr对碳载Pt纳米颗粒进行可控改性，从而生成具有确定组成的纳米合金颗粒。随后在5% H₂/N₂中进行热处理，形成了独特的Pt₃Cr合金相，该相要么局限于颗粒表面，要么存在于整个颗粒结构中。使用旋转薄膜电极法完成了催化剂氧还原活性的测量，所获得的活性与纳米合金催化剂颗粒的结构相关，其结构主要通过Cr K边和Pt L₃边X射线吸收光谱（XAS）确定。
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